Help my pc wont boot up

[Velasco2131]

My pc wont boot up what is the possible reason iam missing a screw on the motherboard and it has preinstalled screws the case is from corsair (750d) i plugged it in after i finished building it and the h100i led turned on the gpu lileds turned on and case leds turned on but wont boot up to the bios help please!

 

[alexoiu]

Try testing it outside the case, see if working.